1. Field of the Invention
The present invention relates to a reservoir for storing a pressurized fluid as well as the method for manufacturing same.
2. Description of the Prior Art
The American patent U.S. Pat. No. 3,508,677 or the French patent FR-A-2 630 810 teaches a reservoir storing a pressurized fluid comprising, on the one hand, an inner shell having a form of revolution about a longitudinal axis with a cylindrical portion and two end pieces, at least one of these end pieces bulging outwardly and comprising a neck and, on the other hand, a wrapping of fibers (glass, carbon, Kevlar (registered trademark) boron, etc...) coated with a hardenable binder completely surrounding said shell, while leaving said neck free.
In such a known reservoir, said inner shell serves as wrapping mandrel for said fiber wrapping and, in order to carry out said wrapping easily by winding, said binder is chosen of a heat hardenable type. Thus, in a method for manufacturing such reservoirs, it is necessary to have as many mandrels as reservoirs to be produced and to subject each reservoir to prolonged treatments at high temperatures so as to obtain appropriate hardening (polymerization) of said heat-hardenable binder.
These known reservoirs are therefore costly. On the other hand, they have high performances and can withstand high inner pressures, of several hundred bars.
However, when it is desired to obtain lower performance reservoirs, withstanding for example internal pressures of only a few tens of bars, it is not economically advantageous to provide the structure of the known reservoirs described above for such lesser performance reservoirs.
Furthermore, for example from the international patent application WO-A-84 00351 and from the French patent FR-A-2 579 130, methods are known for forming hollow bodies by wrapping fibers coated with thermoplastic binder. In these known methods, the fibers coated with thermoplastic binder (so not very flexible at ambient temperature) are wrapped on a mandrel while undergoing at the same time the action of a tracking heating device, causing partial melting thereof in the vicinity of the mandrel so as to facilitate wrapping thereof on said mandrel by softening them and/or binding the consecutive turns of the wrapping solidly together by welding. It is obvious that the heat generated by this tracking heating device must be precise, so that partial melting of the fibers coated with the thermoplastic binder is sufficient to make wrapping thereof and/or welding of said turns possible, without however being excessive so as not to damage said fibers. The regulation of this heat supply is relatively simple to obtain when the speed of application of the fibers is constant, for example during production of a tubular hollow body, but becomes impossible when this speed of application varies, which would be the case in forming bottoms of a reservoir by wrapping.
Therefore, use of this known technique is only possible for producing tubes. In addition, the use of this known technique requires hollow mandrels which remain imprisoned in the tubes after wrapping of the fibers coated with a thermoplastic binder or solid mandrels which have to be destroyed after such wrapping. In both cases, as many mandrels are required as tubes to be formed.